Interpretive Summary: A primary goal of grazing-based forage production systems is to provide high quality forage year-round,reducing costs of using harvested, stored or purchased feeds. The primary forage resources for livestock production in the southern Great Plains are winter wheat and warm-season perennial grasses. Wheat forage is available during winter and early spring. Warm- season perennial grasses are productive only during the late spring and early summer, and their quality declines during mid and late summer. No high-quality forage is available in late summer and fall. Pigeon pea is a summer legume with excellent drought tolerance that is used extensively in Asia for both human food (grain) and for forage. We evaluated seasonal forage production patterns and nutritive value of three pigeon pea cultivars. Forage yields were high relative to alternative grasses and legumes, ranging from 1120 kg ha-1 in July to 12600 kg ha-1 in the first week of October. Nitrogen content and dry matter digestibility also compared favorably with other alternatives. Based on its excellent production and quality in late summer when other forages are unproductive, pigeonpea may have potential for filling the summer/fall gap in a year- round supply of high quality forage.

Technical Abstract:
Agriculture in portions of the southern Great Plains is based on winter wheat (Triticum aestivum L) and stocker cattle production. The primary forage resources are winter wheat pasture during the early winter and spring and warm-season perennial grasses during late spring and summer. However, a void in livestock nutrient supply exists from late July through late November, when quality and quantity of summer perennial grasses have declined and winter wheat forage is not yet available for grazing. To determine if pigeon pea (Cajanus cajan (L.) Millsp.) Could fill this deficit period, a field study was conducted from 1996 to 1998. Seasonal forage production patterns and yield and quality of three pigeonpea ecotypes (ICP8151, ICPX910007, and PBNA) were evaluated. Pigeonpeas produced 5 Mg ha-1 dry matter by August 26, with N content >20g kg-1 and digestibility >500 g kg-1. Ecotype ICPX910007 accumulated greatest dry matter (16 Mg ha-1), followed by ICP8151 (13 Mg ha-1) and PBNA (9.5 Mg ha-1). The dwarf, long-duration ecotype (PBNA) produced less stem dry matter but greater stem N concentration as compared with tall medium- to long-maturity ecotypes. Mean nitrogen concentration for PBNA was 28.6 g kg-1 as compared to about 23 g kg-1 for ICP8151 and ICPX910007, respectively. Dry matter digestibility of PBNA was 614 g kg-1, followed by 576 and 572 for ICP8151 and ICP910007, respectively. Environmental conditions such as cooler spring or summer temperatures and excess rainfall (1997) or extreme drought (1998) reduced yield of all ecotypes. However, our results suggest that pigeonpea has the potential to provide high quality forage that could be used as a primary or supplementary feed for grazing livestock at a time when other forage crops are less productive.